package demo;

import java.util.LinkedList;
import java.util.Queue;

public class MyStack {

    private Queue<Integer> queue1;
    private Queue<Integer> queue2;

    public MyStack() {
        queue1 = new LinkedList<>();
        queue2 = new LinkedList<>();
    }

    public void push(int x) {
        if (!queue1.isEmpty()){
            queue1.offer(x);
        }else if (!queue2.isEmpty()){
            queue2.offer(x);
        }else {
            queue1.offer(x);
        }

    }

    public int pop() {
        if (empty()){
            return -1; // 此处说明栈为空
        }
        if (!queue1.isEmpty()){
            int size = queue1.size();
            for (int i= 0;i<size-1;i++){
                int tmp = queue1.poll();
                queue2.offer(tmp);
            }
            return queue1.poll();
        }else {
            int size = queue2.size();
            for (int i= 0;i<size-1;i++){
                int tmp = queue2.poll();
                queue1.offer(tmp);
            }
            return queue2.poll();
        }
    }

    public int top() {
        if (empty()){
            return -1; // 此处说明栈为空
        }
        int tmp = -1;
        if (!queue1.isEmpty()){
            int size = queue1.size();
            for (int i= 0;i<size;i++){
                tmp = queue1.poll();
                queue2.offer(tmp);
            }
            return tmp;
        }else {
            int size = queue1.size();
            for (int i= 0;i<size;i++){
                tmp = queue2.poll();
                queue1.offer(tmp);
            }
            return tmp;
        }


    }

    public boolean empty() {
        return queue1.isEmpty() && queue2.isEmpty();
    }







}
